The present invention relates to the general field of coatings for protection against erosion. More particularly, the invention relates to an aircraft engine part coated in a coating for protection against erosion.
In operation, airplane or helicopter engines suck in large quantities of air. The air that is sucked in is subsequently compressed in order to feed the combustion chamber with oxidizer. The air may carry particles of greater or smaller hardness that strike the stationary or moving parts inside the engine. Thus, the parts impacted by such particles at high speed can have their shapes modified by erosion, which can lead to failures of the engine.
It is known to make use of sand filters, in particular in helicopter engines, in order to reduce the presence of particles in the engine. Nevertheless, such filters allow a small quantity of particles to pass through, which suffices to damage the parts of the engine in the long term.
It is also known to use anti-erosion coatings that are deposited on the parts of the engine that are subjected to erosion. For example, it is known, to deposit metal nitrides (of the TiN, TiAlN, AlCrN, etc. type) on a part by physical vapor deposition (PVD) or by chemical vapor deposition (CVD). Nevertheless, such coatings generally do not withstand sufficiently the temperatures needed for making the part, and the methods serving to form such coatings do not make it possible to coat parts that are complex in shape.
It is also known to deposit a coating based on hexavalent chromium on metal parts by electrodeposition. Such a method is capable of coating parts that are complex in shape. Nevertheless, such coatings generally do not present sufficient hardness for the above-mentioned application to withstanding erosion.
Document GB 2 180 558 discloses a method of fabricating a chromium-based coating that includes a step of depositing chromium and chromium carbides Cr3C2 on a metal alloy part by plasma spraying, and a step of heat treating the coating for a duration of longer than 200 hours (h). That method is not suitable for treating parts of complex shapes and it presents the drawback of taking a long time, in particular because of the long duration of the heat treatment.
There therefore exists a need to have an aircraft engine part coated in a coating for protection against erosion that does not present the above-mentioned drawbacks, and also a method of fabricating such a part.